1. Field of the Invention
The present invention relates to a communication system including a wireless terminal, a plurality of base stations capable of wireless communication with the wireless terminal, a management apparatus, and a relay apparatus for relaying communication between the plurality of base stations and the management apparatus, and a method for controlling the communication system.
2. Description of the Related Art
In recent years, along with a prevailing 802.11 wireless local area network (LAN) (hereinafter, referred to as a wireless LAN), home network systems capable of a stream communication of video data via the wireless LAN has being developed.
U.S. Patent Application Publication No. US 2007/0047480 discusses a management apparatus that manages wireless resources used by a plurality of access point apparatuses. The management apparatus discussed in U.S. Patent Application Publication No. US 2007/0047480 designates an access point apparatus to be connected for a wireless terminal according to usage of the wireless resource by each access point apparatus. For example, when the wireless resources of the first access point apparatus to which the wireless terminal is connected are exhausted, the management apparatus instructs the wireless terminal to switch connection to a second access point apparatus having spare wireless resources. The wireless terminal switches the connection to the second access point apparatus according to the instruction from the management apparatus and continues wireless communication. As described above, the management apparatus is provided in a network so that each wireless terminal can perform a stream communication using a suitable wireless resource in the system.
Further, Japanese Patent Application Laid-Open Nos. 2000-059380 and 2003-198558 discuss a method for managing an Internet Protocol (IP) address and a Media Access Control (MAC) address of a wireless terminal when an access point apparatus to be connected to the wireless terminal is switched in response to the movement of the wireless terminal.
Consider a case where a management apparatus that manages wireless resources of a plurality of access point (base station) apparatuses is connected to the plurality of access point apparatuses via a bridge. Two wireless terminals performing a stream communication via the first access point apparatus switch connection to the second access point apparatus according to an instruction from the management apparatus. In this case, the two wireless terminals can continue the stream communication via the second access point apparatus.
On the other hand, an IP message from the management apparatus to the wireless terminals, which have switched the connection destination to the second access point apparatus, may not reach the wireless terminals. This is because a forwarding table, which is managed by the bridge, is not updated and, thus, the bridge, which has received the IP message from the management apparatus, forwards the IP message to the first access point apparatus, to which the wireless terminals have been connected earlier. As a result, the wireless terminals cannot receive an important control message from the management apparatus.